Some help with setting timing 5.0 stroked

[hatchssv8]

Gents, I have posted this on another forum as well. The ECM experts here may have a different suggestion. Thanks .

""Got the motor run in yesterday, no problems at all. very happy so far
Of course all is good when you are running between 2 and 3 thousand rpm.

I set static advance at 10 degrees. then fired up straight away.

Today I am looking at tidy up stuff, fitted the thermostat, air box etc etc.

I want to know if I should change the timing (at the dizzy) to assist with a 'smoother' idle

Specs are Holden 5 stroked to 5.7. 9.5:1 comp Crane CD228-88, (retarded by 2 degrees) 228 duration @.050 , total duration 294, 110 separation.
I am running injected with a stock HSV 215 memcal. (Basically a HSV spec motor with Cam and springs changed

OH, total lift about 0.485 in

Any suggestions? ""

[Jayme]

leave the dizzy at 10 deg and wind the idle spark up to about 25 degrees in the tune. it will help the idle a lot.
i did a 355 with flat tops and a crane 286 ish cam this is the idle spark (100kpa at the bottom)

24.61
24.61
24.61
24.61
24.61
24.61
24.61
23.91
21.45
18.98
17.58

make sure u change it in the main spark map and the idle spark map

[hatchssv8]

Thanks, I will try that.
When I adjust in the Main spark map, do I change for both 400 and 800 rpm columns or only the 800.
What did you do there?

[Jayme]

Disclaimer: This spark map was by no means a dyno perfected spot on map, nor have I spent much time smoothing out all the part throttle areas. it was made on the road with hope, gut feeling and a keen ear. should get you on the right track.

355 spark.jpg (166.58 KiB) Viewed 4637 times

[hatchssv8]

I'll try that.

I was also advised to change the idle speed to about 950 to compensate for the cam.

The same person also thought that if I have not changed the checksum in the bin, I would have problems. I am about to check, but from memory I did not change to $AA but left it at $5B. Is there any issue here?

[Jayme]

it depends if the xdf you have calculates the checksum correctly, AA just disables the code form checking the checksum. I usually change it to AA just to be safe. youll know if it dont work... engine light straight on and stuck in limp mode.
950 idle sounds about right for a big cam, I think we had it in the 900's in the 355 I tuned from memory

[madmaxisback]

leave the dizzy at 10 deg and wind the idle spark up to about 25 degrees in the tune. it will help the idle a lot.
i did a 355 with flat tops and a crane 286 ish cam this is the idle spark (100kpa at the bottom)

24.61
24.61
24.61
24.61
24.61
24.61
24.61
23.91
21.45
18.98
17.58

make sure u change it in the main spark map and the idle spark map

Thanks mate... This got me close with less hunt